An isolated 1 V Josephson voltage reference

We operate a 1 V Josephson Junction array continuously in a low-loss storage dewar with only a small increase in the rate of helium loss. Microwave power at 86 GHz is applied to the array via an unclad dielectric waveguide and is switched by moving an absorber close to the guide. The operation of the array is fully automated and the array is biased and its voltage determined by an isolated bias source and voltmeter, either of which can be disconnected after the array voltage has been set.